Brassica species are used world-wide as a source of vegetable oil, animal feeds, vegetables and condiments. The most economically important use of Brassica species is for the production of seed-derived, vegetable oils. Brassica species that are grown primarily for oil production are often called oilseed rape. In North America, canola, a type of oilseed rape that has been selected for low levels of erucic acid and glucosinolates in seeds, is the predominant Brassica plant grown for the production of vegetable oil for human consumption.
Biotechnology has been used in Brassica species for many reasons, including canola variety improvements, yield increase, stress tolerance, modified oil consumption, and other improved traits such as herbicide tolerance. Regarding herbicide tolerance in the commercial production of brassica crops, it is desirable to easily and quickly eliminate unwanted plants (i.e., “weeds”) from the field of Brassica plants. An ideal treatment would be one which could be applied to an entire field but which would eliminate only the unwanted plants while leaving the crop plants unharmed. One such treatment system would involve the use of crop plants which are tolerant to one or more herbicide(s) so that when the herbicide was sprayed on a field of herbicide-tolerant crop plants, the crop plants would continue to thrive while non-herbicide-tolerant weeds were killed or severely damaged.
Because weed control is needed for profitable canola production in addition to other reasons, herbicide tolerant varieties of canola have been developed to be resistant/tolerant to certain herbicides. The ability of herbicide-resistant canola to control a broad spectrum of weeds has led to rapid adoption of the technology. Reduced tillage, increased yields, and improved weed control are several examples of the benefits of herbicide-resistant canola technology. However, it is known that the response of canola to herbicide applications is highly dependent on the herbicide resistant system that is being used in the particular field.
Three main groups of herbicide tolerant canola varieties exist and include, but are not limited to, glyphosate tolerant, glufosinate tolerant or imidazolinone tolerant varieties. The first two groups were developed using genetic modification while the third was developed using traditional plant breeding techniques. Triazine-tolerant canola has also been developed.
Strategic herbicide application timing in herbicide tolerant canola varieties results in economic impact for canola producers because weed density and weed biomass are major restraints in canola production. There is a possibility for several applications of herbicides in herbicide-resistant canola crops. For example, producers may apply an herbicide before planting as an alternative to tillage to manage weed emergence. Once the canola crop has emerged, herbicides may be applied to control post-emergent weeds. Crop staging is one of the major drivers for determining appropriate herbicide application timing in canola.
This disclosure relates to methods of applying glyphosate to improve weed control in a field containing herbicide tolerant brassica species, and more specifically, glyphosate tolerant brassica species.